From EP 0 820 559 B1 and EP 0 886 725 B1 an intake manifold model for calculating state variables and/or operating variables inside the intake tract of an internal combustion engine is known. The calculation is effected in this case on the basis of physical regularities and characteristic maps and parameters, which reflect the operating behavior of the components disposed in the intake tract. These characteristic maps and parameters may be supplied either by the manufacturer of the respective component or by means of tests on suitable test stands. The data thus obtained are however mean values for a limited number of tested components. Because of ageing and manufacturing tolerances of the components, deviations of the actual values of the parameters from the stored mean value may individually arise. As this has consequences for the accuracy of the intake manifold model, the resulting inaccuracies have to be compensated by adaptation processes. Known adaptation processes are based mostly on a comparison between an operating parameter calculated by means of the intake manifold model and a corresponding sensor value. If a deviation between the two values is detected, then the parameters of the intake manifold model may be corrected accordingly, thereby improving the accuracy of the intake manifold model.
Compared to naturally aspirated engines, supercharged internal combustion engines have a larger number of components in the intake tract, which have a considerable influence on the state variables of the intake air and a mutual influence on one another in the operating behavior. Whilst a deviation of the variables calculated by the intake manifold model from the corresponding measured variables may be detected, there is no known method that allows an allocation of the cause of the deviation to the individual components and hence a corresponding correction of the intake manifold model.